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A new test for plant bioaccessibility in sulphidic wastes and soils: a case study for the Wheal Maid historic tailings repository in Cornwall, UK

Citation

van Veen, EM and Lottermoser, BG and Parbhakar-Fox, A and Fox, N and Hunt, J, A new test for plant bioaccessibility in sulphidic wastes and soils: a case study for the Wheal Maid historic tailings repository in Cornwall, UK, Science of The Total Environment, 563-564 pp. 835-844. ISSN 0048-9697 (2016) [Refereed Article]

Copyright Statement

Copyright 2015 Elsevier B.V.

DOI: doi:10.1016/j.scitotenv.2016.01.054

Abstract

Currently, bioaccessibility testing at contaminated sites is dominated by techniques designed to assess oral bioaccessibility to humans. Determining the plant bioaccessibility of toxic trace elements is also important. In mining landscapes, sulphides are an important source of potentially toxic elements. Simple tests to evaluate readily leachable metals and metalloids exist but do not extract elements temporarily constrained within the sulphide fraction. Sequential extractions describe the association of trace elements with different geochemical fractions but are time consuming, costly and provide excessive detail.

This paper proposes a new test for plant bioaccessibility in sulphidic mine wastes and soils that uses hydrogen peroxide to simulate environmental oxidation. The bioaccessible fraction determined is operationally defined and does not predict actual plant uptake. The test targets a) the portion of an element that is currently available in the pore water for uptake by plant roots and also b) the fraction that is temporarily constrained in sulphide minerals but may become available upon oxidation of the substrate. A case study was conducted at a historic mine waste repository site in Cornwall, U.K. where near total As concentrations were extremely elevated and Cd, Cu, Pb, Sb and Zn were also high. Our test determined that bioaccessible concentrations of As, Cd, Cu and Zn and to a lesser extent Sb and Pb were highest in samples of pyritic grey tailings. This is attributed to sulphide mineral oxidation and, particularly for Cd and Zn, the dissolution of soluble secondary minerals. High As concentrations in the marbled tailings were not bioaccessible.

Results from the case study show that this new test provides useful information on the future bioaccessibility of contaminants, allowing for classification of mineralised sulphidic waste materials which otherwise cannot be obtained using established geochemical and mineralogical techniques. Furthermore, the test is rapid, repeatable and cost effective.

Item Details

Item Type:Refereed Article
Keywords:bioaccessibility, mine waste, accelerated oxidation, potentially toxic metals and metalloids, mine site closure
Research Division:Earth Sciences
Research Group:Geochemistry
Research Field:Geochemistry not elsewhere classified
Objective Division:Environment
Objective Group:Land and Water Management
Objective Field:Mining Land and Water Management
Author:Parbhakar-Fox, A (Dr Anita Parbhakar-Fox)
Author:Fox, N (Dr Nathan Fox)
ID Code:106393
Year Published:2016
Deposited By:Earth Sciences
Deposited On:2016-02-09
Last Modified:2017-01-27
Downloads:0

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